A copper wire has a square cross-section, 2.0 mm on a side. It carries a current of 8 A and the density of free electrons is `8 xx 10^(28)m^(-3)`. The drift speed of electrons is equal to

Options

A. `0.156xx10^(-3)ms^(-1)`
B. `0.156xx10^(-2)ms^(-1)`
C. `3.12xx10^(-3)ms^(-1)`
D. `3.12xx10^(-2)ms^(-1)`

Answer

1

Explanation

`I=nAev_(d)`
or `v_(d)=(- I)/(nAe)ms^(-1)`
or `v_(d)=(8)/((8xx10^(28))xx(2xx10^(-3))xx1.6xx10^(-19)) ms^(-1)`
` =(8)/(8xx2xx2xx1.6xx1 000)ms^(-1)`
`=0.156xx10^(-3)ms^(-1)`